Heavy Metals Poisoning

miners with their hands and feet in water with electrical wires attached Since the early days of mining in the Silver Valley, mining companies have tried innovative methods to deal with lead poisoning in miners. Lead poisoning was a serious health risk for smelter workers dealing with lead oxide, but much less so for the miners.

One early attempt to cure lead poisoning, called the Clague Process, passed an electric current through a miner's body while his hands and feet were immersed in water. The Bunker Hill Company hospital used this method for several years, but it ultimately proved totally ineffective.

Lead in Children

While lead poisoning can affect adults, it is particularly troublesome in young children. High blood lead levels in children cause permanent IQ loss, can cause hearing and balance problems, tooth decay, and kidney and nervous system damage.

bunker hill smelterA century of mining in the Silver Valley resulted in extensive lead contamination throughout the Silver Valley. Lead is found in the thousands of tons of mine tailings that stretch for miles through the basin. Children who play in the dirt in the summer tend to have higher blood lead levels than in other times of the year.

The lead smelter operating at Bunker Hill dumped tons of lead oxide into the air, particularly after a 1973 fire in the smelter's bag house filtration system. For almost a year, the owners of Bunker Hill continued to run the smelter without adequate filtration of lead particulates. During this time, stack emissions averaged about 35 tons of lead per month. Afterwards, blood lead levels in many Silver Valley children registered some of the highest in the world, several times the acceptable lead level estabished by the Centers for Disease Control and Prevention. They have established an acceptable blood lead level of 10 µg/dL. And some experts say 0 µg/dL is the preferred level.

backyard in kelloggSince Bunker Hill and the surrounding 21 square mile area was declared a Superfund site in 1983, lead levels in children have dropped substantially. That's because the cleanup has concentrated on removing contaminated soils from the homes of residents and hauling in clean dirt. An extensive educational program was also conducted, to make parents aware of the problems with lead.

According to Jerry Cobb of the Panhandle Health District, "I think back in maybe 1989, we had around almost 50% of our kids with a blood level of 10 or greater. Now we're down with less than 2%. So it's been just a tremendous amount of progress."

Most experts believe there is still a risk to children of chronic, low-level lead exposure throughout the area, and that constant vigilance is required.

Zinc in the water

While lead is the serious problem on the ground, zinc is the serious problem in the water. Zinc in moderate doses is not a problem in humans, but it is deadly to fish.

The EPA is beginning to address this issue in some of the valley's streams. Zinc is one of the heavy metals flowing out of the Bunker Hill mine on a daily basis. A water treatment plant is treating this almost two million gallons per day, before it is released into the South Fork of the Coeur d'Alene River.